LEVEL DETECTION CIRCUITRYLevel Detectorslocation. Using relays, this system provides alarms on high and low level. It may also providecontrol functions such as repositioning a valve and protective features such as tripping a pump.EnvironmentalConcernsDensity of the fluid whose level is to be measured can have a large effect on level detectioninstrumentation. It primarily affects level sensing instruments which utilize a wet reference leg.In these instruments, it is possible for the reference leg temperature to be different from thetemperature of the fluid whose level is to be measured. An example of this is the level detectioninstrumentation for a boiler steam drum. The water in the reference leg is at a lower temperaturethan the water in the steam drum. Therefore, it is more dense, and must be compensated for toensure the indicated steam drum level is accurately indicated.Ambient temperature variations will affect the accuracy and reliability of level detectioninstrumentation. Variations in ambient temperature can directly affect the resistance ofcomponents in the instrumentation circuitry, and, therefore, affect the calibration ofelectric/electronic equipment. The effects of temperature variations are reduced by the designof the circuitry and by maintaining the level detection instrumentation in the proper environment.The presence of humidity will also affect most electrical equipment, especially electronicequipment. High humidity causes moisture to collect on the equipment. This moisture can causeshort circuits, grounds, and corrosion, which, in turn, may damage components. The effects dueto humidity are controlled by maintaining the equipment in the proper environment.IC-03 Page 16 Rev. 0